Cover tape for sealing chip-holding parts of carrier tape

ABSTRACT

A cover tape for sealing chips in chip-holding parts of a carrier tape having said parts provided discontinuously and longitudinally of said carrier tape, which cover tape comprises a base tape, an adhesive layer formed on one surface of said base tape and a non-adhesive coat formed on said adhesive layer along the longitudinal direction of said base tape so that said non-adhesive coat has a width broader than that of the chips and narrower than that of said adhesive layer. When the cover tape is used in combination with the carrier tape, the chip-holding parts are sealed by the cover tape having the non-adhesive coat and in consequence the chips held in the chip-holding parts do not come in contact with the adhesive layer although they might come in contact with the non-adhesive coat. Accordingly, the chips are not stained by the adhesive in the adhesive layer.

This application is a Rule 1.60 division of Ser. No. 07/447,440, filedDec. 7, 1989, now U.S. Pat. No. 4,994,300, which in turn is a Rule 1.60divisional of Ser. No. 07/224,016, filed July 25, 1988, now U.S. Pat.No. 4,929,486.

FIELD OF THE INVENTION

The present invention relates to a cover tape for sealing chips-holdingparts of a carrier tape which is used for packaging chips, such as smallelectronic parts, arranged longitudinally of said carrier tape and inspaced apart relation, for the purpose of storage, transportation andautomatic taking out thereof. The invention also relates to a processfor the preparation of such a cover tape.

BACKGROUND OF THE INVENTION

Recently, electronic parts such as resistances, condensers andintegrated circuits have been miniaturized and used in the form ofchips. To cope with such a tendency, various devices for packaging suchchips suitable for use in storage, transportation and automatic takingout of the packaged chips have been proposed. Among others, devicesbased on a carrier tape appear to have the most promising prospects.

Such devices may be roughly classified into two types: (a) one using acarrier tape having apertures punched out, as disclosed in JapaneseUtility Model Laid-open Publication No. 58-7.399, and (b) the otherusing an embossed carrier tape, as disclosed in Japanese Utility ModelLaid-open Publications Nos. 62-65,959 and 61-202,362.

In the first type of devices, use is made, as a carrier tape, of arelatively thick tape of paper having a row of apertures of a requireddimension formed along the center line of the tape with a predeterminedinterval between successive apertures. Normally, another row of holesare provided along one of side edges of the carrier tape for a deliverypurpose. A bottom tape is attached to one surface of the carrier tape sothat each aperture may form a chip-holding room. After chips have beenplaced in respective chip-holding rooms, a cover tape is attached to theother surface of the carrier tape so as to seal the chips in position.

In the second type of devices, as shown in FIG. 4, use is made, as acarrier tape, of an embossed plastic tape 3 having a row of depressedparts (chip-holding parts 1) of a required dimension formed embossmentalong the center line of the tape with a predetermined interval betweensuccessive parts. Normally, another row of holes 2 are provided alongone of side edges of the carrier tape for a delivery purpose. Afterchips 4 have been placed in respective chip-holding parts, a cover tape5 is attached to the surface of the carrier tape so as to seal the chips4 in position.

In both the types of devices, use is made of a cover tape 5, whichnormally comprises a base plastic tape 6 and a layer 7 of a heatsensitive adhesive formed on the base tape 6, which adhesive is inactiveat ambient temperature and becomes active only when heated. Such a covertape 5 is adhered to the carrier tape by application of heat andpressure particularly to those areas adjacent to the chip-holding parts1.

The cover tape is required that it can firmly adhere to the carrier tapeon the one hand. On the other hand, upon taking out the stored chips, itis required that the cover tape can be peeled off from the carrier tapeby a relatively weak force. Further, the chips must not be stained bythe adhesive constituting the adhesive layer 7. In other words, thechips 4 should not come in contact with the adhesive layer 7 at leastunder conditions where the adhesive is active.

For these requirements, hot melt adhesives have heretofore beengenerally employed to constitute the adhesive layer 7. However, problemshave been associated with the hot melt adhesives in that the cover tape5 must be adhered to the carrier tape 3 under heat along both side edgesof the cover tape 5 of a width of on the order of about one millimeter,frequently resulting in non-uniform adhesion. The step of adhesion underheat is also disadvantageous from the view point of the productive speedof the production line, and might invite undesirable heat deformation ofthe carrier tape 3. Further, in a case wherein the chips 4 are stored ortransported at an elevated temperature, the hot melt adhesive isreactivated and might come in contact with the chips 4 to stain them.

OBJECT OF THE INVENTION

The invention is to solve the problems associated with the prior art andan object of the invention is to provide a cover tape which can be usedin combination with a known carrier tape having chip-holding parts forsealing the chip-holding parts of the carrier tape and which does notstain the chips. Another object of the invention is to provide a processfor the preparation of such a cover tape.

SUMMARY OF THE INVENTION

A cover tape according to the invention for sealing chips inchip-holding parts of a carrier tape having said parts provideddiscontinuously and longitudinally of said carrier tape, comprises abase tape, an adhesive layer formed on one surface of said base tape anda non-adhesive coat formed on said adhesive layer along the longitudinaldirection of said base tape so that said non-adhesive coat has a widthbroader than that of the chips and narrower than that of said adhesivelayer.

A process for the preparation of a cover tape according to the inventionfor sealing chips in chips-holding parts of a carrier tape having saidparts provided discontinuously and longitudinally of said carrier tape,comprises the steps of forming an adhesive layer on one surface of abase tape, and pattern-printing a non-adhesive coat on said adhesivelayer along the longitudinal direction of said base tape so that saidnon-adhesive coat has a width broader than that of the chips andnarrower than that of said adhesive layer.

EFFECT OF THE INVENTION

According to the invention the chip-holding parts of the carrier tapeare sealed by the cover tape having the non-adhesive coat so that thechips placed in the chip-holding parts of the carrier tape do not comein contact with the adhesive layer of the cover tape although they mightcome in contact with the non-adhesive coat of the cover tape, and inconsequence the chips are not stained by the adhesive constituting theadhesive layer of the cover tape.

Further, those portions of the adhesive layer of the cover tape whichare not occupied by the non-adhesive coat can uniformly and effectivelyadhere to those parts of the carrier tape other than the chip-holdingparts to provide stable adhesion and peeling, and in consequenceadhesion and peeling of the cover tape is easy and simple.

In cases wherein an antistatic agent is incorporated in the non-adhesivecoat, the cover tape is prevented from being charged with staticelectricity, thereby effectively preventing damage of the chips bystatic charge and attraction of the chips to the cover tape upon peelingthe cover tape which attraction might be a cause of falling off of thechips.

Further, in cases wherein a pressure-sensitive adhesive which is stickyat ambient temperature is used to constitute the adhesive layer of thecover tape, adhesion of the cover tape to the carrier tape can beeffected without using heat and pressure, ensuring not only easyprocessing but also uniform adhesion without a risk of heat deformationof the carrier tape.

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described in detail with reference to theattached drawings in which:

FIG. 1 (A) is a partly cross-sectional perspective view of a cover tapeaccording to one embodiment of the invention;

FIG. 1 (B) is a partly cross-sectional perspective view of a cover tapeaccording to another embodiment of the invention;

FIG. 2 is a partly cross-sectional perspective view of an assemblycomprising an embossed carrier tape and a cover tape according to theinvention,

FIG. 3 is a partly cross-sectional perspective view of an assemblycomprising a carrier tape having apertures and tw cover tapes accordingto the invention, and

FIG. 4 is a partly cross-sectional perspective view of an assemblycomprising an embossed carrier tape and s cover tape according to priorart.

As shown in FIG. 1 (A), a cover tape 10 according to one embodiment ofthe invention comprises a transparent base tape 11, an adhesive layer12, which is preferably sticky at ambient temperature, formed all overone of the surfaces of the base tape 11 and a non-adhesive coat 13having a predetermined width formed on the adhesive layer 12.

While the non-adhesive coat 13 extends along the longitudinal directionof the cover tape 10, the width of the non-adhesive coat 13 is widerthan that of chips 4 held in chips-holding parts 1 of a carrier tape 3and narrower than that of the adhesive layer 12, as shown in FIG. 2. Thewidth of the non-adhesive coat should preferably be as same as the widthof the chips-holding parts 1 of the carrier tape 3, as shown in FIG. 2.By doing so the chips 4 held in the parts 1 will be almost completelyprevented from being brought in contact with the adhesive layer 12 ofthe cover tape 10. For example, in a case wherein the carrier tape 3 hasa width of 8 mm, the cover tape 10 has a width of 5.3 mm, and the chipshave a width of not greater than 3 mm, the width of the non-adhesivecoat may be on the order of 3.3 mm.

The cover tape 10 according to this embodiment can be prepared byforming an adhesive layer 12 on one surface of a base tape 11, andpattern-printing a non-adhesive coat 13 on said adhesive layer 12 sothat the non-adhesive coat may extend continuously along thelongitudinal direction and may have a predetermined width.

Materials of the base tape 11 include polyethylene terephthalate (PET),polypropylene (PP), high density polyethylene, polystyrene, polyimideand polyvinyl chloride. Of these, PET is particularly preferred. Thethickness of the base tape 11 normally from 6 to 200 μm, preferably from10 to 100 μm.

Preferred pressure-sensitive-adhesives which can be used to form theadhesive layer 12, are those which are sticky at ambient temperature,such as acrylic and methacrylic adhesives and rubber-based adhesives.Examples of (meth) acrylic adhesives include, for example, homopolymersand copolymers of (meth) acrylic acid esters such as ethyl, butyl,2-ethyhexyl, glycidyl and 2-hydroxyethyl acrylates and methacrylates,and copolymers of at least one of such (meth) acrylates with at leastone copolymerizable monomer such as vinyl acetate, acrylic acid,methacrylic acid, styrene and acrylonitrile. Examples of therubber-based adhesives include, for example, natural rubbers (NR),polyisobutylene rubbers (IR), butadiene rubbers (BR), styrene-butadienerubbers (SBR) and styrene-isoprene-styrene block copolymer(SIS), aloneor in combination, as well as blends of at least of such rubbers with atleast one other tackifiers such as rosin and terpene resins. Thethickness of the adhesive layer 12 is normally from 5 to 100 μm,preferably from 10 to 50 μm.

The non-adhesive coat 13 is advantageously formed by pattern-printingwith either oxidation curable inks based on linseed oil, tung oil,soybean oil and synthetic drying oils, or radiation-curable inks basedon urethane acrylate, epoxy acrylate, polyester acrylate and polyethers.The ink used may be colored or may not be colored. Radiation-curableinks, in particular ultraviolet ray-curable inks, which are curable to ahigh crosslink density, are generally preferred. After a predeterminedpattern of the coat 13 has been printed on the adhesive layer 12 with aradiation-curable ink, the printed pattern is subjected to irradiation,in particular ultraviolet ray-irradiation, to cure the ink, renderingthe pattern-printed coat non-adhesive. The non-adhesive coat 13 soformed does not stain chips, even if it comes in contact with the chips.The thickness of the non-adhesive coat 13 is normally from 0.1 to 20 μm,preferably from 1 to 10 μm.

The ink, and in turn the non-adhesive coat 13 made therefrom, maycontain an antistatic agent such as surfactants. By doing so, thenon-adhesive coat 13 becomes antistatic, and thus it is possible toprevent damage of chips by static charge and static attraction of chipswhich might cause chips to fall off. Suitable antistatic agents whichcan be used herein include, for example, quarternary ammonium salts,aliphatic sulfonates, salts of higher alcohol sulfates, salts of higheralcohol phosphates, ethylene oxide adducts to higher alcohols andpolyethylene glycol esters of fatty acids.

In cases wherein an antistatic agent is incorporated in the non-adhesivecoat 13, the cover tape 10 is prevented from being charged with staticelectricity, thereby effectively preventing damage of the chips 4 bystatic charge and attraction of the chips 4 to the cover tape 10 uponpeeling the cover tape which attraction might be a cause of falling offof the chips 4.

Further, in cases wherein a pressure-sensitive adhesive which is stickyat ambient temperature is used to constitute the adhesive layer 12 ofthe cover tape 10, adhesion of the cover tape 10 to the carrier tape 3can be effected without using heat and pressure, ensuring not only easyprocessing but also uniform adhesion without a risk of heat deformationof the carrier tape 3.

While the invention has been described with reference to FIG. 1 (A) andFIG. 2, it is not restricted thereto. Modifications within the scope theappended claims well be apparent to s person skilled in the art.

For example, the carrier tape 10 according to the invention can be usedin combination with an embossed carrier tape, as illustrated in FIG. 2.Likewise, as shown in FIG. 3, it can be used in combination with acarrier tape 3a having a row of apertures (chip-holding parts 1a) of arequired dimension formed along the center line of the tape with apredetermined interval between successive apertures. In this case twocover tapes 10 are adhered to both surfaces of the carrier tape 3a,respectively.

Further, as shown in FIG. 1 (B), a cover tape according to the inventionmay comprise a base tape 11, an adhesive layer 12 formed on one surfaceof said base tape 11, a non-adhesive coat 13 formed on said adhesivelayer 12 along the longitudinal direction of said base tape so that saidnon-adhesive coat 13 has a width broader than that of the chips andnarrower than that of said adhesive layer 12, and a layer of a releasingagent 14 formed on the opposite surface of said base tape 11. The covertape 10a is stored in the form of a roll before use. At this state, thelayer 14 advantageously provides the adhesive layer 12 of the rolledcover tape 10a with a releasing surface. Examples of the releasing agentwhich can be used to form the layer 14 include, for example, silicone,stearyl acrylate and stearyl maleate; and copolymers thereof withacrylic acid, methyl acrylate, acrylonitrole, maleic acid or styrene. Ofthese, copolymers of stearyl acrylate are particularly preferred.

Chips 4 that can be placed in the chip-holding parts 1, 1a of thecarrier tape 3. 3a may be small mechanical parts and pharmaceuticaltablets as well as small electronic parts.

While the invention has been described on the cases wherein the adhesivelayer 12 is composed of a pressure-sensitive adhesive which is sticky atambient temperature, the adhesive layer 12 may comprises aheat-sensitive adhesive. Examples of the heat-sensitive adhesive whichcan be used herein include, for example, ethylene-vinyl acetate rubber(EVA), styrene-butadiene rubber (SBR), ionomeric rubber, polybutadienerubber (BR), styrene-isoprene-styrene block copolumer(SIS) andstyrene-ethylene-butadiene-styrene block copolumer(SEBS).

While the invention will now be further described by the followingexamples, it is not restricted thereto.

EXAMPLE 1

One of the surfaces of a polypropylene film having a thickness of 40 μmwas coated with a terpolymer of 2-ethylhexyl acrylate, vinyl acetate andacrylic acid to form a pressure-sensitive adhesive layer having athickness of 20 μm. On the adhesive layer so formed a pattern of apredetermined width extending longitudinally of the tape was printedwith a transparent, ultraviolet ray-curable, polyester acrylate-basedink. The printed coat was cured by ultraviolet ray irradiation. Thecured coat had a thickness of about 6 μm.

The effect of the invention can be confirmed with the cover tape soprepared.

EXAMPLE 2

One of the surfaces of a polyethylene terephthalate film having athickness of 25 μm was coated with a styrene-butadiene block copolymerto form a heat-sensitive adhesive layer having a thickness of 20 μm. Onthe adhesive layer so formed a pattern of a predetermined widthextending longitudinally of the tape was printed with a transparent,ultraviolet ray-curable, epoxy acrylate-based ink. The printed coat wascured by ultraviolet ray irradiation. The cured coat had a thickness ofabout 6 μm.

The effect of the invention can be confirmed with the cover tape soprepared.

What is claimed is:
 1. A device for packing chips comprising:a carriertape having chip-holding parts provided intermittently andlongitudinally of said carrier tape; and a cover tape on said carriertape for sealing chips in said chip-holding parts, said cover tapeincluding: a base tape, an adhesive layer formed on only one surface ofthe base tape, and a non-adhesive layer containing an oxidation-curedink and pattern-printed on the adhesive layer centrally along thelongitudinal direction of the base tape so that the non-adhesive layerhas a width greater than that of the chips and covering saidchip-holding parts, and less than that of the adhesive layer with theparts of said adhesive layer which are free of said non-adhesive layeradhered to said carrier tape.
 2. A device for packing chips comprising acarrier tape having chip-holding parts provided intermittently andlongitudinally of said carrier tape; anda cover tape on said carriertape for sealing chips in said chip-holding parts, said cover tapeincluding: a base tape, an adhesive layer formed on only one surface ofthe base tape, and a non-adhesive layer containing an antistatic agentand pattern-printed on the adhesive layer centrally along thelongitudinal direction of the base tape so that the non-adhesive layerhas a width greater than that of the chips and covering said chips andholding parts, and less than that of the adhesive layer with the partsof said adhesive layer which are free of said non-adhesive layer adheredto said carrier tape.
 3. A device for packing chips comprising:a carriertape having chip-holding parts provided intermittently andlongitudinally of said carrier tape; and a cover tape on said carriertape for sealing chips in said chip-holding parts, said cover tapeincluding: a base tape, an adhesive layer formed on only one surface ofthe base tape, and a non-adhesive layer containing a radiation-cured inkand pattern-printed on the adhesive layer centrally along thelongitudinal direction of the base tape so that the non-adhesive layerhas a width greater than that of the chips and covering saidchip-holding parts, and less than that of the adhesive layer with theparts of said adhesive layer which are free of said non-adhesive layeradhered to said carrier tape.